Modern commercial vehicles include conventional electrical supply systems. These systems provide low voltage DC to vehicle manufacturer provided systems. Most commercial vehicles are produced by an original equipment manufacturer (OEM) and later are provided with customer equipment. The customer equipment could at one time have been powered from the OEM provided electrical system without any strain on the system. The customer application equipment varies widely, however examples would include refrigeration systems for produce delivery vehicles or trucks to fire pumps for fire trucks to towing winches on tow trucks.
As the end user applications have grown so have their power requirements. Alternator capacity for the latest in medium-duty diesel powered trucks is a 100-amp capacity. Heavy-duty trucks with home-like conveniences such as microwave cooking ovens have a demand in the 2400 watts range with a 164-amp alternator. For trucks with added customer application equipment, OEMs estimate total vehicle capacity will be 3000 watts with the next generation of engine controls expected to demand more. When the OEM electrical system capacity has been exceeded, customers have relied upon diesel powered auxiliary systems beyond the vehicles main engine or electro-hydraulic generators with hydraulic energy supplied by an engine mounted power take-off (PTO) from the vehicle's main engine. The issues for these solutions include cost, system control, and lack of efficiency. An additional auxiliary diesel engine adds cost as well as inconvenience. The control would be separate from the main vehicle engine. Electro-hydraulic generators are direct linked to the main engine through the PTO. This is inefficient in that energy is wasted on these units even when the customer energy consumption devices are not in use.
There is a need for an integrated vehicle energy management system that provides the energy for the increasing customer application needs without reducing the overall vehicle energy efficiency and is controlled by an integrated control system.